Abstract: The present subject matter provides a capillary viscometer for use in measuring concentration and shear dependence of the viscosity of macromolecular solutions. In one embodiment the device can automatically make serial dilutions of a single initial sample and record viscosity measurements across wide concentration ranges without changing samples. The device and associated methods can be used to rapidly and accurately assay solute stability and potentially solute-solute interactions in solutions of proteins and other macromolecules of pharmaceutical interest over a wide range of concentrations, including those corresponding to pharmaceutical formulations.